You create the image of an object, a creature, or some other visible phenomenon that is no larger than a 20-foot Cube. The image appears at a spot that you can see within range and lasts for the duration. It seems real, including sounds, smells, and temperature appropriate to the thing depicted, but it can’t deal damage or cause conditions.
If you are within range of the illusion, you can take a Magic action to cause the image to move to any other spot within range. As the image changes location, you can alter its appearance so that its movements appear natural for the image. For example, if you create an image of a creature and move it, you can alter the image so that it appears to be walking. Similarly, you can cause the illusion to make different sounds at different times, even making it carry on a conversation, for example.
Physical interaction with the image reveals it to be an illusion, for things can pass through it. A creature that takes a Study action to examine the image can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC. If a creature discerns the illusion for what it is, the creature can see through the image, and its other sensory qualities become faint to the creature.
Using a Higher-Level Spell Slot. The spell lasts until dispelled, without requiring Concentration, if cast with a level 4+ spell slot.
* - (a bit of fleece)
The spell isn't dismissed if you cast it again, and you can cast it without concentration and until dispelled with a level 4+ spell slot? So a caster with the spell could feasibly have as many major images as they've had level 4+ spell slots since they've had them, and control it at any time in the future as long as they are within range. A creature with access to this spell and level 4+ slots could create a veritable menagerie of illusions all over the place.
Can this spell make two or more creatures?
Two or more crates?
What is considered a visible phenomena? Rain? Smoke? Fire?
As an illusionist wizard, I REALLY appreciate this buff. With the additional wizard spells for subclasses allowing me to pick actually thematic spells instead of having to give up on fireball, dispel magic, and other crucial 3rd level spells I really like instead of just the illusion spells for thematic reasons and the buffs to the upcasting requirement being even lower, I might actually get to use it during a campaign instead of having to wait until level 11 when many campaigns end.
rain, smoke, and fire would all fall be visible phenomena I would say, and considering that this illusion explicitly effects all the senses, you could likely use this and similar illusions to block vision similar to fog cloud or any spell that creates a blockade, except you know it's an illusion so you can see through it.
So if I read this correctly, it's a static image UNLESS I move it to a different location? So I can't make an illusion of person move it's mouth to have a conversation while standing still - I'd have to make them walkaround the room as they talk... This seems clunky... Is the intention to use the magic action to make it move in any way, regardless of whether its location is changed?
It doesn't have to be static while in place. You need to use a magic action to move it between new squares or you can use a magic action later to have a character making a new conversation.
So can you touch/feel the illusion? I only ask because of the wording of “Physical interaction with the image reveals it to be an illusion, for things Can pass through it.”
No, you can't touch or feel the illusion. Because of the thing you quoted.
Ok so if you theoretically create an image of a nuclear fusion. Wouldn't just the temprature of this image, which is mentioned in the spell to be there, still be unberable to even be remotley close and actually damage a creature that is close to it, aswell as blind anything close to it?
No, because the spell explicitly says it can't deal damage or impose conditions.
Is that inconsistent with the idea of it having "appropriate temperature"? Yes, it is. But this is magic; by definition it does not have to obey normal physical laws.
You can create the illusion of that, but it can't deal damage or cause conditions, because there would only be an illusion of light and heat. Thus:
You would see a light so bright it ought to be blinding, but it isn't.
You would feel a heat so intense it ought to be painful, but it isn't.
And anyone who experiences that would likely immediately know it was an illusion, and discerning it as an illusion, as the spell says, causes it to become see-through and the other effects to become faint.